Now, I can ping 172.17.10.1, so the tunnel is up and running right. I want all of the IPs for a specified destination , 172.29.0.0/20, to go through this tunnel. Some are binded to some VLAN interfaces locally, some remote that use me as a gateway.

I've tried

$ ip ro add somedest/24 via 172.17.10.1 dev mytunnel

Doing ping somedest -I 172.29.5.22 fails, did a tcpdump and nothing shows up as going through the tunnel.